The presently disclosed embodiments relate generally to layers that are useful in imaging apparatus members and components, for use in electrophotographic, including digital printing, apparatuses. More particularly, the embodiments pertain to an improved electrophotographic imaging member comprising a very thin outer layer on an imaging member surface, where the very thin outer layer comprises functional healing materials that act as a lubricant and or a barrier against moisture and/or surface contaminants. The very thin outer layer is applied to the imaging member on a nano-scale or molecular level. The improved imaging member exhibits improved xerographic performance, such as improved interaction with a blade cleaner and reduced image deletions in high humidity conditions. The embodiments also pertain to methods and systems for delivering the healing materials to the surface of the imaging member.
In electrophotographic or electrophotographic printing, a charge retentive surface, typically known as a photoreceptor, is electrostatically charged, and then exposed to a light pattern of an original image to selectively discharge the surface in accordance therewith. A resulting pattern of charged and discharged areas on the photoreceptor form an electrostatic charge pattern, known as a latent image, conforming to the original image. The latent image is developed by contacting it with a finely divided electrostatically attractable powder known as toner. Toner is held on image areas by the electrostatic charge on the surface of the photoreceptor. Thus, a toner image is produced in conformity with a light image of an original being reproduced or printed. The toner image may then be transferred to a substrate or support member (e.g., paper) directly or through the use of an intermediate transfer member, and the toner image affixed thereto to form a permanent record of the original to be reproduced or printed. Subsequent to development, excess toner left on the charge retentive surface is cleaned from the surface. The process is useful for light lens copying from an original or printing electronically generated or stored originals such as with a raster output scanner (ROS), where a charged surface may be imagewise discharged in a variety of ways.
The described electrophotographic copying process is well known and is commonly used for light lens copying of an original document. Analogous processes also exist in other electrophotographic printing applications such as, for example, digital laser printing or ionographic printing and reproduction where charge is deposited on a charge retentive surface in response to electronically generated or stored images.
A scorotron has been employed to charge a surface of a photoreceptor. Alternatively, to charge a surface of a photoreceptor, a contact type charging device has been used. The contact type charging device, also termed “bias charge roll” includes a conductive member which is supplied a voltage from a power source with a D.C. voltage superimposed with an A.C. voltage of no less than twice the level of the D.C. voltagen The charging device contacts an image bearing member (photoreceptor) surface, which is a member to be charged. The outer surface of an image bearing member is charged with the a rubbing friction at a contact area. The contact type charging device charges the image bearing member to a predetermined potential. Typically the contact type charging device is in the form of a roll charger such as that disclosed in U.S. Pat. No. 4,387,980, the relative portions thereof incorporated herein by reference. Further, a vicinity type of charging roller may also be suitable to charge a photoreceptor surface, such as in U.S. Pat. No. 6,360,065.
Electrophotographic photoreceptors can be provided in a number of forms. For example, the photoreceptors can be a homogeneous layer of a single material, such as vitreous selenium, or it can be a composite layer containing a photoconductive layer and another material. In addition, the photoreceptor can be layered. Multilayered photoreceptors or imaging members have at least two layers, and may include a substrate, a conductive layer, an optional undercoat layer (sometimes referred to as a “charge blocking layer” or “hole blocking layer”), an optional adhesive layer, a photogenerating layer (sometimes referred to as a “charge generation layer,” “charge generating layer,” or “charge generator layer”), a charge transport layer, and an optional overcoating layer in either a flexible belt form or a rigid drum configuration. In the multilayer configuration, active layers of the photoreceptor are the charge generation layer (CGL) and the charge transport layer (CTL). Enhancement of charge transport across these layers provides better photoreceptor performance. Multilayered flexible photoreceptor members may include an anti-curl layer on a backside of the substrate, opposite to the side of the active layers, to render a desired photoreceptor flatness.
Conventional photoreceptors are disclosed in the following patents, a number of which describe the presence of light scattering particles in the undercoat layers: Yu, U.S. Pat. No. 5,660,961; Yu, U.S. Pat. No. 5,215,839; and Katayama et al., U.S. Pat. No. 5,958,638. The terms “photoreceptor” or “photoconductor” is generally used interchangeably with the terms “imaging member.” The term “electrophotographic” includes “electrophotographic” and “xerographic.” The term “charge transport molecule” is generally used interchangeably with the term “hole transport molecule.”
To further increase the service life of the photoreceptor, use of overcoat layers has also been implemented to protect photoreceptors and improve performance, such as wear resistance. However, these low wear overcoats are associated with poor image quality due to deletion in a humid environment as the wear rates decrease to a certain level. The low wear overcoated photoreceptors also often possess high friction with a blade cleaner, thus causing inefficient cleaning. The high friction may also increase the risk of cleaning blade damage at an earlier stage. Therefore, in order to improve the image quality and service life of a low wear photoreceptor there is a need to control the surface chemistry of the photoreceptor due to charging and to minimize its deletion. Further there is a need to improve the interaction between the low wear photoreceptor and a blade cleaner for reduced friction and improved cleaning.